Order Publications

Abstracts

In recent years, SF6/N2 gas mixtures was getting used as insulating medium in many gas-insulated equipment because of the greenhouse effect and poor economy of pure SF6 gas. This paper studied on the synergistic effect of SF6/N2 gas mixtures with low SF6 mixing ratio in slightly non-uniform electric field under positive and negative lightning impulse. The research indicates that the synergistic effect of SF6/N2 gas mixtures breakdown voltage under negative lightning impulse or positive lightning impulse was appeared obviously. The breakdown voltage under negative lightning impulse is higher than which under positive lightning impulse with low SF6 mixing ratio, but when SF6 mixing ratio exceeds a critical value, the breakdown voltage under negative lightning impulse is lower. The synergistic effect coefficient was introduced to the quantitative analysis of synergistic effect. The analysis result shows that the synergistic effect is more significant with negative lightning impulse than positive, and the synergistic effect coefficient which is hardly affected by gas pressure is less than 0.1. In contrast to that, the synergistic effect which is enhanced with the increase of gas pressure is less remarkable with positive lightning impulse. The research result has important engineering practical value for SF6/N2 gas mixtures applied in the electric power equipment such as GIL, and it also has theoretical significance for gas discharge mechanism of SF6/N2 gas mixtures.